Foreign matter inspection apparatus

ABSTRACT

Selection with alignment marks of an optimal template, its identification and similarity judgment are conducted by a calculation function of a correlation value provided to a foreign matter inspection apparatus. In other words, the foreign matter inspection apparatus includes unit for registering feature points of alignment marks formed on a surface of an inspected object, unit for collecting image data of the alignment marks formed on the surface of the inspected object and a data processor for extracting a feature point from the image data and calculating a correlation value of both feature points, and registers the image data of the alignment mark on the basis of a threshold value of the correlation value.

BACKGROUND OF THE INVENTION

This invention relates to a foreign matter inspection apparatus fordetecting foreign matters, scratches, defects, contamination, and soforth (which will be altogether referred to as “foreign matters”)existing on a surface of an inspected object such as a glass substrate,a semiconductor wafer, or the like. More particularly, the inventionrelates to a foreign matter inspection apparatus for highly preciselycorrecting a position of an inspected object and detecting foreignmatters with high accuracy and high sensitivity.

An apparatus for detecting the existence of foreign matters existing ona surface of an inspected object such as a glass substrate and asemiconductor wafer by irradiating an optical beam such as a laser beamto the surface of the inspected object and detecting a reflected orscattered beam occurring from the surface is known as a foreign matterinspection apparatus for (refer to JP-A-5-47901). In this foreign matterinspection apparatus, an image signal is generated from the intensity ofreflected or scattered beams detected from each chip when a large numberof IC chips originally having the same pattern are formed on asemiconductor wafer, and this image signal is compared with an imagesignal obtained from an adjacent chip or with an image signal from anapproved chip prepared in advance. A matter on the surface of thesemiconductor wafer is judged as the foreign matter when a differencebetween these image signals is greater than a threshold value.

When the image signal described above is collected, chips juxtaposed ina transverse direction on the surface of the inspection object must beput in parallel with a scanning direction of the optical beam. Becausethe difference signal is collected through comparison with the adjacentchips, variance occurs in the difference signal owing to the kind of thepattern contained in the detection region or the difference of thedensity such as wiring layout inside the chips and scribe lines amongthe chips and the inspection result is adversely affected.

As an alignment method for arranging parallel the inspected object, amethod has been employed that collects coordinates (X, Y) of two pointsinside the inspected object with alignment marks formed inside the chipson the surface of the inspected object as the reference, and moves aninspection stage for correction on the basis of the deviation amount ofthe inspected object calculated from the coordinates.

Detection of foreign matters having smaller sizes has become necessaryin recent years with the increase of an integration density and furtherminiaturization of semiconductors. To suppress variance of the errorsignal and to improve detection accuracy and reproducibility, higheralignment accuracy has been required. Nonetheless, alignment has becomemore and more difficult owing to miniaturization of the alignment marksand the drop of contrast resulting from the manufacturing process.

A method that prepares a projection waveform of a reticle substrate asreference image data (hereinafter called “template”) and determines anerror amount from pattern matching with a projection waveform obtainedin practice from a position adjustment rectile substrate is known as analignment method of an inspection position (refer to JP-A-10-106941, forexample).

As for pattern matching methods, a method that detects an image signalfrom an inspection object, extracts a predetermined feature amount fromthe image signal to form an abstracted pattern and executes patternmatching between this abstracted pattern and an abstracted patternobtained from the reference image (template) is known (refer toJP-A-11-340115, for example).

When a position error of a pattern wafer put on a movable stage isautomatically aligned in an inspection apparatus for inspecting apattern wafer, chips are aligned accurately and precisely on the patternwafer. To inspect the pattern wafers, the wafers must be aligned in Xand Y directions of a stage. However, immediately after the wafers aretransferred to the stage, the wafers are not correctly aligned in the Xand Y directions and must be positioned in the X and Y directions byrotating the stage.

To align the pattern wafers, a plurality of correction marks is formed,a CCD camera is used to image the positions of the correction marks andthese positions are measured by a pattern matching process. A rotationangle of the stage to be corrected is then calculated from a pluralityof points.

Generally, imaging is made in alignment by using two kinds ofmagnification cameras. To improve accuracy of the correction angle to becalculated, the positions of the correction marks must be detected withhigh accuracy. However, the imaging visual field of the magnificationcamera is narrow and the probability of covering the correction marks bya single imaging operation becomes low. For this reason, a system hasbeen employed that detects a rough position by a low magnificationcamera and then accuracy is improved by switching the camera to a highmagnification camera.

However, this system involves the problem that alignment needs a longtime. To improve inspection through-put, it would be conceivable toderive an optimal magnification ratio from alignment accuracy and apositioning error of the stage at the time of transfer and to conductalignment at a single magnification. JP-A-11-220006 can be cited as oneof the references relating to this technology.

In alignment at a single magnification, however, three or more marks ofcorrection marks for calculating a correction angle for detecting arecognition error of other pattern as a correction mark and confirmationmarks for confirming alignment accuracy are necessary. When the wafer istransferred to the stage, the center of the wafer deviates from thecenter of the stage and the coordinate position of the correction markfor confirmation deviates, too. Therefore, the coordinate position ofthe confirmation mark must be detected before correction. However, themovement of the stage and the pattern matching processing becomenecessary and the processing time gets elongated. The coordinates of theconfirmation mark must be therefore calculated in advance from thecoordinates of the correction mark detected.

The technology described in JP-A-10-106941 executes a collectivecorrection processing of a position error amount between going andreturning strokes when an inspected object is scanned in going andreturning directions by optical beams. This technology cannot be appliedto a foreign matter inspection apparatus that requires high precisionalignment of individual inspected objects. Since the technology isdirected to a reticle substrate produced as a jig that is dedicated tothe adjustment of the positioning error, it does not take intoconsideration those adverse influences which may be exerted on variouskinds of thin films produced in the manufacturing process ofsemiconductor devices such as semiconductor films, metal films,insulating films, and so forth, and problems of the recognition failuredue to the drop of contrast of the alignment marks and the matchingmistake with other alignment marks are unavoidable.

It has been customary in the past for an operator to select an alignmentmark while watching an observation screen of an inspected object and toregister the image data as a template. When an inspection process ofsemiconductor device products is a manufacturing process which invitesthe drop of contrast, however, it is difficult to observe the alignmentmarks with eye. Therefore, the operator empirically repeats selection ofthe alignment marks but a long time is necessary to set a complicatedevaluation condition of the template and a collection work. Furthermore,when an error of an angle (θ) occurs in the inspected object, it isdifficult to use the template as such and correction of the angle isnecessary. The error of the correction process results in the drop andvariance of alignment accuracy.

SUMMARY OF THE INVENTION

It is an object of the invention to conduct pattern matching in such afashion as not to invite recognition failure and recognition mistakeeven when alignment marks of an inspected object are under a difficultcondition for conducting pattern matching.

It is another object of the invention to make it easy to select asuitable template and to set an evaluation condition by providingfunctions of analyzing whether or not an image of a pattern collectedfrom an inspection object is suitable as a template and registering theresult.

It is still another object of the invention to improve inspectionthrough-put of an inspection apparatus.

In a foreign matter inspection apparatus for inspecting the existence offoreign matters on a surface of an inspected object by irradiatingoptical beams to the surface of the inspected object, acquiring an imagesignal from a reception intensity of reflected or scattered beams andcomparing the image signal with an image signal acquired from anadjacent inspected object, the foreign matter inspection apparatusaccording to the invention comprises a device for registering featurepoints of alignment marks formed on the surface of the inspected object;and a device for reading the alignment marks on the surface of theinspected object; wherein alignment is executed by detecting thealignment marks formed on the surface of the inspected object on thebasis of the feature points.

In a foreign matter inspection apparatus for inspecting the existence offoreign matters on a surface of an inspected object from a receptionintensity of reflected or scattered beams from the inspected object byirradiating optical beams to the surface of the inspected object, theforeign matter inspection apparatus according to the invention comprisesa device for inputting feature points of alignment marks formed on thesurface of the inspected object; a device for displaying the featurepoints of the alignment marks inputted; and a device for registeringfeature points of the alignment marks inputted; wherein alignment isconducted by detecting the alignment marks formed on the surface of theinspected object on the basis of the feature points.

In a foreign matter inspection apparatus for inspecting the existence offoreign matters on a surface of an inspected object from a receptionintensity of reflected or scattered beams by irradiating optical beamsto the surface of the inspected object, the foreign matter inspectionapparatus according to the invention comprises a device for registeringfeature points of alignment marks formed on the surface of the inspectedobject; a device for collecting image data of the alignment marks formedon the surface of the inspected object; and a data processor forextracting feature points from the image data and calculating acorrelation value from both of the feature points; wherein the imagedata of the alignment marks are registered on the basis of a thresholdvalue of the correlation value.

In a foreign matter inspection apparatus for inspecting the existence offoreign matters on a surface of an inspected object from a receptionintensity of reflected or scattered beams by irradiating optical beamsto the inspected object, the foreign matter inspection apparatusaccording to the invention comprises a device for registering featurepoints of alignment marks formed on the surface of the inspected object;a device for collecting image data of the alignment marks formed on thesurface of the inspected object; a data processor for extracting featurepoints from the image data and calculating a correlation value from bothof the feature points; and a display device for displaying a calculationresult of the correlation value; wherein a judgment result ofapproval/rejection of the alignment marks is displayed on the basis of athreshold value of the correlation value. It is preferred in thisforeign matter inspection apparatus that the calculation result of thecorrelation value is arranged in the order of the size of thecorrelation values and is displayed in a list form on the displayapparatus described above.

In a foreign matter inspection apparatus for inspecting the existence offoreign matters on a surface of an inspected object by irradiatingoptical beams to the surface of the inspected object, acquiring an imagesignal from a reception intensity of reflected or scattered beams andcomparing the image signal with an image signal acquired from anadjacent inspected object, the foreign matter inspection apparatusaccording to the invention comprises image processing unit forextracting feature points of alignment marks formed on the surface ofthe inspected object and conducting pattern matching with feature pointsof a template; processing means for calculating a probability or scorefrom both of the feature points subjected to pattern matching; judgmentprocessing unit for identifying an alignment mark as a reference whenthe feature points are coincident with one another with a predeterminedprobability or score; another processing unit for calculating adifference amount of the inspected object from coordinates collected byrecognition of at least two alignment marks inside the inspected object;and a driving mechanism for conducting alignment by moving an inspectionstage on the basis of the difference amount.

To automatically select an optimal alignment mark or marks in theinvention, the foreign matter inspection apparatus according to theinvention may be provided with an evaluation function of the alignmentmarks as to whether or not the image data is suitable as a template, adisplay function of displaying the evaluation result, a selectionfunction of the alignment marks and a registration function of storingthe image data as the template.

To automatically extract the alignment mark as a template candidate, theforeign matter inspection apparatus may further include data input meansfor inputting the feature points of the template, data registrationmeans for storing data, detection means for collecting the image data ofa designated zone inside a chip on the basis of the feature points ofthe template, data registration means for storing the image datacollected, image processing means for extracting the feature points fromthe image data, a data processing unit for comparing the feature pointsof the template stored, display means for displaying coordinates of thealignment mark collected and its appearance, and analytical valuescalculated by the data processing unit such as suitability number andsuitability rank, and registration means for registering image data byautomatically selecting the alignment mark as an optimal template fromamong the alignment marks.

To evaluate in advance the possibility of the recognition error of thetemplate candidate, the foreign matter inspection apparatus may furthercomprises detection unit for collecting image data of a designated zoneinside a chip on the basis of the feature points of the templatecandidate extracted, data registration unit for storing the image datacollected, image processing means for extracting the feature points fromthe image data, a data processing unit for comparing the feature pointsof the template stored, and display unit for displaying coordinates ofthe image data collected and its appearance and analytical valuescalculated by the data processing unit such as suitability number andsuitability rank.

One of the features of the invention for accomplishing the objectsdescribed above resides in a foreign matter inspection apparatus whichcomprises unit for detecting coordinates of marks of two points forcorrection, unit for calculating a correction angle of a wafer from thecoordinates of the correction marks of the two points, unit forcalculating the coordinates of a mark for confirmation from thecorrection angle of the wafer, the coordinates of the correction markand coordinates of confirmation mark registered in advance when thewafer is transferred to a stage, unit for calculating the coordinates ofthe confirmation mark when the stage is rotated by the correction angle,unit for detecting the coordinates of the confirmation mark, and unitfor comparing the coordinates of the confirmation mark detected with thecoordinates of the confirmation mark calculated when the stage isrotated. This and other features of the invention will become moreapparent from the following description.

According to the invention, pattern matching can be executed whilerecognition failure and recognition error of the alignment marks aresuppressed.

According to the invention, inspection through-put of the inspectionapparatus can be improved. When alignment is made, for example, aninclination of the wafer is calculated from coordinates of two pointsand correction accuracy must be confirmed after the correction is made.Detection of the coordinates of the two points for confirmation is timeconsuming and the time can be shortened by detecting the coordinates ofone other point. However, the center of the stage deviates from thecenter of the wafer after transfer of the wafer and the positions of theconfirmation marks are also deviated, and a detection of theconfirmation marks is required. When the positions of the confirmationmarks are calculated by taking the deviation of the center between thestage and the wafer into account, alignment can be conducted without thenecessity for detecting the confirmation marks before correction.

Other objects, features and advantages of the invention will becomeapparent from the following description of the embodiments of theinvention taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view showing a rough construction of a foreign matterinspection apparatus according to the invention;

FIG. 2 is a block view showing an outline of control of a dataprocessing unit:

FIG. 3 is an explanatory view useful for explaining chips and designatedcoordinates used for alignment inside a semiconductor wafer;

FIG. 4 is an explanatory view useful for explaining a processing of edgeintensity waveform and edge positions;

FIG. 5 is an explanatory view useful for explaining a set screen ofalignment;

FIG. 6 is an explanatory view useful for explaining a CAD screen forplotting a template candidate;

FIG. 7 is an explanatory view useful for explaining an example of thetemplate candidate;

FIG. 8 is an explanatory view useful for explaining designatedcoordinates and a designation range for evaluating the templatecandidate;

FIG. 9 is an explanatory view useful for explaining a set screen forevaluating the template candidate;

FIG. 10 is an explanatory view useful for explaining a screen thatdisplays an evaluation result of the template candidate;

FIG. 11 is an explanatory view useful for explaining a set screen thatinspects alignment marks formed inside a chip of a semiconductor wafer;

FIG. 12 is an explanatory view useful for explaining a screen thatdisplays an inspection result of alignment marks formed inside a chip ofa semiconductor wafer;

FIG. 13 is an explanatory view useful for explaining a set screen thatevaluates reliability of the template candidate;

FIG. 14 is a flowchart that represents a method of angle correction of asemiconductor wafer by using a template;

FIG. 15 is a flowchart that represents a method for collecting anoptimal template;

FIG. 16 is a flowchart that represents a method for inspecting atemplate candidate inside a semiconductor wafer;

FIG. 17 is a flowchart that represents a method for evaluatingreliability of the template candidate and for selecting an optimaltemplate;

FIG. 18 is a structural view of an inspection apparatus according to anembodiment of the invention;

FIG. 19 shows correction marks on a wafer by alignment;

FIG. 20 shows the wafer and movement of the correction marks byalignment; and

FIG. 21 is a processing flowchart showing an execution method ofalignment.

DESCRIPTION OF THE INVENTION

Embodiments of the invention will be hereinafter explained in detailwith reference to the accompanying drawings. A foreign matter inspectionapparatus according to the invention can inspect those foreign matterswhich exist on a surface of an inspected object such as a semiconductorwafer, an ALTIC substrate and a glass substrate used for TFT-LCD, butthe following explanation will be directed to the semiconductor wafer asan example of the inspected object.

An embodiment of the invention that improves a processing speed ofalignment and detects recognition error of marks by using two correctionmarks and one confirmation mark will be explained.

Embodiment 1

FIG. 1 is a plan view showing a rough construction of a foreign matterinspection apparatus according to an embodiment of the invention. Theforeign matter inspection apparatus includes one or more load ports 10,a transfer unit 20, a pre-alignment unit 30, an inspection unit 40 and adata processing unit 50. One or more wafer cassettes 11 accommodating aplurality of semiconductor wafers 1 to be inspected is put on the loadports 10. The wafer cassettes 11 may be divided into those fortransferring the semiconductor wafers 1 to be inspected and those forrecovering the semiconductor wafers 1 that are judged as defective as aresult of inspection.

FIG. 2 is a block view showing an outline of control of the dataprocessing unit 50. The data processing unit 50 includes a host computer100, an input device 110 such as a keyboard, a touch panel or a mouse, adisplay device 120 such as a CRT or a flat panel display, an outputdevice 130 such as a printer and an external storage device 140 forcontrolling external media such as a floppy (registered trade mark) disk(FD) or a compact disk (CD). The host computer 100 has a data processor150 and a storage device 160 such as a hard disk drive (HDD). The hostcomputer 100 controls the entire foreign inspection apparatus on thebasis of the instruction from the input device 110. The display device120 displays control relating to alignment, the result of analysis,control of the inspection condition, analysis of data collected and theoperating condition of the foreign matter inspection apparatus andfurthermore, outputs these data to the output device 130 such as theprinter. Setting of the various conditions is inputted through the inputdevice 110 and is stored as recipe data in the storage device 160.

FIG. 14 is a flowchart showing a processing procedure of thesemiconductor wafer 1 in the first embodiment. In the foreign matterinspection apparatus shown in FIG. 1, transfer of the semiconductorwafer 1 is carried out as a signal is transmitted from the dataprocessing unit 50 upon execution of a transfer program (S101), a servomotor is driven through a pulse control substrate and a driving circuit,not shown, and a handling arm 22 provided to a transfer assembly 21 iscontrolled. The handling arm 22 takes out the semiconductor wafer 1 fromthe rack of the wafer cassette 11 designated by the data processing unit50 and transfers it to the pre-alignment unit 30 from the load port 10(S102). When the semiconductor cassette 1 is taken out from the wafercassette 11, the wafer cassette 11 is controlled in such a fashion thata substantial center of a U-shaped contact portion 22 a is in conformitywith a substantial center of the semiconductor wafer 1 and thesemiconductor wafer 1 is vacuum adsorbed to and held by an adsorptionopening 23 of the contact portion 22 a.

The handling arm 22 moves forward above the pre-alignment chuck 31 whileholding the semiconductor wafer 1, descends at the position at which thesubstantial center of the semiconductor wafer 1 is coincident with thatof the pre-alignment chuck 31 and mounts the semiconductor wafer 1 ontothe pre-alignment chuck 31. Next, the pre-alignment chuck 31 vacuumadsorbs the back of the semiconductor wafer 1 and holds thesemiconductor wafer 1.

The pre-alignment chuck 31 is so constituted as to be capable of movingand rotating in X, Y and θ directions. The detection device 32 has alight emission unit such as a laser beam, and a light reception unitsuch as a CCD line sensor, detects the position of light reaching thelight reception unit from the light emission unit and its intensity anddetects the outer circumference of the semiconductor wafer 1 and theposition of a V notch (or so-called “orientation flat”). The dataprocessing unit 50 drives the pulse motor through a pulse controlcircuit and a driving circuit, each not shown, on the basis of thedetection result of the detection device 32 and moves and rotates thepre-alignment chuck 31 to thereby execute rough position adjustment(pre-alignment) of the semiconductor wafer 1 (S103).

After pre-alignment is completed, the pre-alignment chuck 31 releasesvacuum adsorption of the semiconductor wafer 1. The handling arm 22moves below the semiconductor wafer 1 that is mounted onto thepre-alignment chuck 31 and moves up at the position at which the centerof the U-shaped contact portion 22 a is substantially coincident withthe center of the semiconductor wafer 1 and lifts up the semiconductorwafer 1 from the pre-alignment chuck 31. The semiconductor wafer 1 isthen transferred from the pre-alignment unit 30 to the inspection unit40 (S104).

An inspection stage chuck 42 is provided to the inspection stage 41 inthe inspection unit 40. The inspection stage chuck 42 has elevation pins43 a, 43 b and 43 c capable of moving up and down. The handling arm 22moves forth above the inspection stage chuck 42 while lifting up thesemiconductor wafer 1 under the state where the elevation pins 43 a, 43b and 43 c are elevated, moves down at the position at which thesubstantial center of the semiconductor wafer 1 is coincident with thatof the inspection stage chuck 42 and delivers the semiconductor wafer 1to the elevation pins 43 a, 43 b and 43 c. Next, after the handling arm22 moves back from the position above the inspection stage chuck 42, theelevation pins 43 a, 43 b and 43 c are lowered and the semiconductorwafer 1 is mounted onto the inspection stage chuck 42. The inspectionstage chuck 42 vacuum adsorbs the back of the semiconductor wafer 1 andfixes the semiconductor wafer 1.

When the semiconductor wafer 1 is placed on the inspection stage chuck42, the data processing unit 50 reads the chip size from the recipe dataregistered to the storage device 160 through the input device 110 andcalculates the coordinates of the chips juxtaposed on the semiconductorwafer 1 by the data processor 150. The inspection stage chuck 42 is soconstituted as to be capable of moving and rotating in the X, Y and θdirections and controls the inspection positions on the semiconductor 1,etc, while detecting the positions (coordinates) by a position detector(not shown in the drawing) such as a laser scale. The data processingunit 50 drives the servo motor (not shown in the drawing) through thepulse control substrate and the driving circuit, each not shown, andmoves and rotates the inspection stage chuck 42 to move it to the firstchip designated coordinates 311 of the first chip 310 shown in FIG. 3,for example (S105).

A CCD camera (not shown) is provided to an upper part of the inspectionstage chuck 42 of the inspection unit 40. The CCD camera searches thedesignated range in the proximity of the first chip designatedcoordinates 311 (S106) and samples the first alignment mark 312 of thefirst chip 310 as image data, for example (S107). The data processor 150calculates mean lightness of the entire image of the image data of thefirst alignment mark 312 so sampled on the basis of gradation data foreach data. Next, a multiplier that makes this mean lightnesssubstantially equal to mean lightness of a template is determined andthe difference between lightness calculated by multiplying thismultiplier for lightness of each pixel and the mean lightness of theentire image is calculated for each pixel. Owing to this normalizationprocessing, the change between the pixels is extracted as normalizedlightness waveforms (projection waveforms) and is stored in the storagedevice 160.

Though the lightness as the reference is the mean lightness of thetemplate in this embodiment, a similar effect can be likewise obtainedby determining a multiplier that adjusts lightness on the basis of setlightness that is in advance set.

The data processor 150 executes a calculation processing of theprojection waveform and calculates an edge intensity waveform 410representing the change of density (gradation) shown in FIG. 4 bydifferentiation, for example. Next, the data processor 150 extracts amaximum edge intensity value 411 representing a maximum value from theedge intensity waveform 410 so obtained, determines a multiplier thatmakes the maximum value substantially equal to a feature amount setvalue 420 set in advance and corrects the entire edge intensity waveform410 on the basis of the multiplier so that the maximum edge intensityvalue 411 becomes high when contrast is low, and low when the contrastis high. This correction restricts influences of the drop of contrastsuch as the change of the film or illumination on the surface of thesemiconductor wafer 1 on pattern matching accuracy.

An edge position 440 is detected from a peak exceeding a feature amountthreshold value 430 registered in advance to the storage device 160 andthe position of the pixel of the CCD on the basis of this thresholdvalue 430 and stores the intensity value of each edge position 440 andthe feature point such as the position of the pixel of the CCD inassociation with the positional information (coordinates information)from the position detector.

The image processing is executed for the data of the template as thereference of comparison in the same way as the first alignment mark 312described above and the intensity value of each edge position 440 andthe feature point such as the CCD pixel position are registered inadvance to the storage device 160. Pattern matching of the firstalignment mark 312 is made on the basis of the feature point of thistemplate and comparison is judged (S108). When the first alignment mark312 is different from the template pattern, for example, search insidethe designated range is continued. Pattern matching is continued byrepeating the steps S106 to S108 and an alignment mark providingcorrelation is searched. A pattern detected with a predeterminedcorrelation is recognized as the first alignment mark 312 and theposition detector detects the coordinates (X, Y) of the first alignmentmark 312. The coordinates are then registered to the storage device 160(S109). Because comparison judgment is made by using the feature pointsthat are mutually normalized, high precision pattern matching can besecured even when the contrast of the first alignment mark 312 is lowowing to the influences of the process steps and the recognition errorcan be suppressed.

The data processor 150 calculates an index value (score value)representing the matching state for the pattern recognized as the firstalignment mark 312 by pattern matching on the basis of the feature pointand displays it on the screen of the display device 120. The score valueis calculated in accordance with equation (1), for example, on the basisof the correlation data of the feature point in the first alignment mark312 and the template. The score value may be calculated by formulasother than equation (1) as long as they can express and display thedegree of pattern matching, and similar effects can be acquired.

[Expression 1]

$\begin{matrix}{S = {\sqrt{\frac{Mp}{Tt}} \times \sqrt{\frac{Mp}{Ta}} \times 10000}} & (1)\end{matrix}$

Incidentally, symbol S in equation (1) represents the score value, Mprepresents the number of coincidences of edges in pattern matching, Ttrepresents the total number of edges at the time of collection of thetemplate and Ta represents the total number of edges of the firstalignment mark 312.

The score value S is stored in the storage device 160 whenever patternmatching of the semiconductor wafer 1 is made and is displayed on thescreen of the display device 120. Whether or not the template isapproved can also be judged, by confirming the pattern matching statethrough the score value S. The state of the alignment mark, that is tosay, the manufacturing condition of semiconductor devices and thecondition of the foreign matter inspection apparatus, can be diagnosedthrough comparison with the data of the past score values S. Display orwarning of abnormality and apparatus abnormality can be transmitted toremote diagnosing means on the basis of the threshold value of the scorevalue S that is set in advance, and they can be set through the inputdevice 110 with selection of display/non-display of the score value S.

After the coordinates of the first alignment mark 312 are detected, theinspection stage chuck 42 is moved to the second chip designatedcoordinates 321 on the chip matrix of the semiconductor wafer 1 (S110).Image processing and pattern matching are executed for the secondalignment mark 322 of the second chip 320 in the same way as the firstalignment mark 312 (S11 to S113). The coordinates (X, Y) of the secondalignment mark 322 are detected and are stored in the storage device 160with the score value calculated (S114). A set value (threshold value) ofa management reference value of this score value can be set from asetting window arranged on the screen of the display device 120. When atleast one of the first alignment mark 312 and the second alignment mark322 does not satisfy the condition of the threshold value, alarm displaycan be made through the data processing unit 50.

Incidentally, the calculation step in the data processing of the scorevalue may be skipped, and the data processing method and the displaymethod can be changed through setting from the input device 110,depending on the condition of the use of the foreign matter inspectionapparatus such as when condition monitor of pattern matching is notnecessary because the occurrence of the recognition error is less orwhen through-put of the foreign matter inspection apparatus is required.

The data processor 150 calculates the difference of the angle from thetwo (X, Y) coordinates of the first alignment mark 312 and the secondalignment mark 322 and the angle of the inspection stage chuck 42 iscorrected on the basis of the instruction from the data processing unit50 (S115). The chips juxtaposed on the semiconductor wafer 1 are puthighly precisely in parallel with the scanning direction of the opticalbeam.

A light projection system apparatus and a light reception systemapparatus, each not shown, are arranged above the inspection stage chuck42 and the optical beam such as a laser beam is irradiated to thesurface of the semiconductor wafer 1 from the light projection systemapparatus. The inspection stage chuck 42 is moved in the Y and Xdirections by driving the servo motor to scan the optical beams on thesurface of the semiconductor wafer 1.

The light reception system apparatus detects reflecting light orscattered light generated from the surface of the semiconductor wafer 1and the host computer 100 of the data processing unit 50 executes dataprocessing on the basis of the detection result of the light receptionsystem apparatus to detect foreign matters that exist on the surface ofthe semiconductor wafer 1 (S116).

After the foreign matter inspection of the surface of the semiconductorwafer 1 is completed, the semiconductor wafer 1 is transferred from theinspection unit 40 to the load port 10 in the reverse procedure to thetransfer of the semiconductor wafer 1 to the inspection stage chuck 42and is stored in the same rack of the same wafer cassette 11.Incidentally, when the number of foreign matters on the surface of thesemiconductor wafer 1 exceeds a set value, the semiconductor waver 1 maybe classified and transferred to the wafer cassette 11 of other loadport 10. Classification and transfer of the semiconductor wafers 1 atthe time of transfer can be set from the input device 110 of the displaydevice 120 through the input device 110.

In this embodiment, correction is made by using the two (X, Y)coordinates but when three or more (X, Y) coordinates positioned invertical and transverse directions are used, higher correction can bemade through the correction time needs a longer time. In thisembodiment, correction is made by the chips of the same row arranged inthe transverse direction relative to the notch of the semiconductorwafer 1, the chip arrangement may be corrected to be parallel to thescanning direction of the optical beam. Similar performance can be thusacquired by correction by chip arrangement in a longitudinal directionor an oblique direction or by an arbitrary chip arrangement.

The greater the distance between the first chip 310 and the second chip320 that are used for the position correction, the higher becomesaccuracy of the angle correction. The alignment mark is likely to comeoff from the designated search range or the recognition error is likelyto occur when predetermined accuracy cannot be obtained for the anglecorrection of the pre-alignment chuck 31. Therefore, designatedcoordinates of an intermediate correction chip 330 are interposedbetween the first chip 310 and the second chip 320 and fine adjustmentof the positioning error between the first chip 310 and the second chip320 can be made after rough position correction is made by using thisintermediate correction chip 330. Selection of the use of theintermediate correction chip and setting of various conditions can beset to the set screen on the display device 120 through the input device110. The alignment mark can be recognized stably even in thosesemiconductor wafers 1 which have large positioning errors by selectionmeans of the positioning error correction method.

FIG. 5 shows the condition setting screen described above. The conditionsetting screen includes chip condition setting means 510 for setting thefirst chip 310, the second chip 320 and the intermediate correction chip330, coordinate condition setting means 520 for setting the coordinatesof the alignment marks such as the first chip designation coordinates311, the second chip designated coordinates 321 and the intermediatecorrection chip designated coordinates, search condition setting means530 for setting the range to be searched, template setting means 540 forsetting the template used for pattern matching, and matching conditionsetting means 550 for setting the correction conditions such as theangle and the position, the data processing method of the score valueand the threshold value. Setting of those conditions and numericalvalues which may govern matching among the set conditions of variousitems are displayed on the set value displaying means 560 at the top ofthe set screen. When each condition setting button is selected throughthe input device 110, the corresponding set screen is opened and eachdetailed data can be set. Though this embodiment uses buttons for theset screen, the set screen may be constituted by using icons, inputspaces or other means as long as display and setting of the screen andthe set condition can be made.

Embodiment 2

To discriminate the alignment marks by pattern matching, a template as acomparison object is necessary. Next, a method of collecting an optimaltemplate from among the patterns formed on the semiconductor wafer 1will be explained by mainly referring to FIGS. 6, 7 and 15. Theexplanation of those portions witch overlap with the first embodimentwill be omitted and reference will be also made to FIGS. 1 and 2,whenever necessary.

FIG. 15 is a flowchart showing the processing procedure of thesemiconductor wafer 1 in the second embodiment and FIG. 6 shows a CAD(Computer Aided Design) screen 720 for plotting a template candidate 710of the alignment mark. The CAD screen 720 is provided as one of thefunctions of the foreign matter inspection apparatus and is displayed onthe screen of the display device 120. The host computer 100 executesvarious processing for the CAD screen 720 on the basis of theinstruction from the input device 110. A grid and a scale can bedisplayed on the CAD screen 720 and a rough size of the templatecandidate 710 can be confirmed. Shape information of the width, heightand angle of the template candidate 710 can be displayed on appearancedisplay means 720. Plotting means 740 for plotting and editing thetemplate candidate 710 such as solid line, broken line, chain line,circle and rectangle, reversion and rotation of graphic, diminishing andenlargement of size, etc, is displayed on the CAD screen 720 by imagessuch as icons, marks or buttons. The template candidate 710 can be readand edited from the external storage device 140 through the storagedevice 160 and a storage medium and can be further saved. Design data ofthe alignment mark can be inputted through the external storage device140. The template candidate 710 matching with the feature points of animage on the screen of the display device 120 that is plotted by freehand through position display means such as a mouse pointer 730 can beread out from the storage device 160 on the basis of this image.

FIG. 7 shows examples of the template candidate 710 used in thisembodiment. The (a) of FIG. 7 shows an candidate formed by arranging arectangle inside an outer profile of a rectangle and disposing acrisscross at the center. The (b) of FIG. 7 shows a candidate formed byjuxtaposing an L-shaped figure with an outer L-shaped profile. The (c)of FIG. 7 shows a candidate formed by chamfering the corners of thepattern shown in the (b) of FIG. 7. The (d) of FIG. 7 shows a candidateformed by arranging a rectangle in the proximity of the pattern sown inthe (c) of FIG. 7.

Figures shown in the (a) to (d) of FIG. 7 are formed by executing theprogram (S201) and are registered as the template candidates forsearching the surface of the semiconductor wafer 1 to the storage device160. When an alignment mark of the same kind existing on thesemiconductor wafer 1 is searched, one or more template candidates 710are selected from the template candidates registered and are enteredthrough the input device 110 (S202). The figures created and registeredin the past can also be read out and used.

To improve matching accuracy, it is generally preferred that thetemplate candidate has a large number of corners and the figure itselfis independent. When the difference of the angle of the semiconductorwafer 1 is great or in the case of the wafer having a low contrastprocess, however, recognition defect may occur. For this reason, thetemplate figure is preferably selected depending on the situation.

The transfer program is executed after the template candidate 710 isselected. The designated semiconductor wafer 1 taken out from the wafercassette 11 of the load port 10 is transferred to the inspection unit 40in the same way as in the first embodiment and is fixed onto theinspection stage chuck 42 (S203 to S205). Incidentally, it is alsopossible to select the template candidate 710 after the semiconductorwafer is fixed to the inspection stage chuck 42 and the operation can beswitched by setting an inspection mode to the one that automaticallyexecutes only the inspection and evaluation process of the templatecandidate 710.

After the semiconductor wafer 1 is fixed onto the inspection stage chuck42, the stage chuck 42 is moved to the template evaluation designatedcoordinates 810 designated in advance by driving the servo motor of thestage chuck 42 in the same way as in the first embodiment (S206). Thetemplate evaluation designated coordinates 810 are arranged as thescreen for evaluating the template candidate 710 on the display device120 as shown in FIG. 9 and one or more coordinates can be set throughthe input device 110. It is thus possible to set a plurality ofcoordinates and to determined mean evaluation result of the templatecandidates 710.

The inspection stage chuck 42 is moved with the template evaluationdesignated coordinates 810 as the starting point and a pattern analogousto the template candidate 710 is searched from among the inspectedpatterns 830 formed inside the designated range 820 of the semiconductorwafer 1 by the CCD camera (S207).

The template candidate 710 registered to the storage device 160 is savedas the image data of line segments. The image of the inspected pattern830 collected through the CCD camera (S208) is image processed into theimage data subjected to line segmentation by the data processor 150 andpattern matching with the template candidate 710 entered is carried out,whenever necessary (S209). When the size is different between thetemplate candidate 710 and the inspected pattern 830 or when an angledifference occurs in the semiconductor wafer 1, pattern matchingaccuracy drops. Therefore, pattern matching is carried out while theimage data of the template candidate 710 is rendered variable (imagecorrection unit) in the matrix shape within the designated range such asangle variable range setting 920 and size variable range 930 (shapecorrection setting unit) and in accordance with a size variable amount991 and an angle variable amount 992 (variable amount setting unit).When a correlation coefficient 910 set in advance is satisfied inpattern matching, the position detector such as a laser scale built inthe inspection stage 41 detects the coordinates of the inspected pattern830.

The score value is calculated in accordance with equation (2), forexample, on the basis of the feature points of the template candidate710 and the feature points of the inspected pattern 830 subjected topattern matching (S210). Calculation of the score value is not limitedto this equation (2) but can be made by other means as long as they cannumerically express and grade the degree of pattern matching. Thefeature points at the time of pattern matching are used as the featurepoints of the inspected pattern 830 and the feature points of thetemplate candidate 710. However, it is possible to separately executethe image processing of the image data of each of them and to use thefeature points extracted by the same or different feature pointextracting unit. Analytical accuracy of the difference between thetemplate candidate 710 and the inspected pattern 830 can be improved bychanging pattern matching and the feature points used for calculatingthe score value.

[Expression 2]

$\begin{matrix}{S = {\sqrt{\frac{Ms}{Ts}} \times \sqrt{\frac{Ms}{Td}} \times 10000}} & (2)\end{matrix}$

Symbol S in equation (2) represents the size of the score value betweenthe template candidate 710 and the inspected pattern 830 that aresubjected to pattern matching. Symbol Ms represents the number ofcoincidence of the feature points between the inspected pattern 830 andthe template candidate 710. Symbol Ts represents the total number of thefeature points of the inspected pattern 830 collected and symbol Tdrepresents the total number of the feature points of the templatecandidate 710.

The score value calculated is registered to the storage device 160 inassociation with the images of the template candidate 710 and the imageof the inspected pattern 830 together with the angle correction value1050 and the size correction value 1060 (correction value calculationunit) that are calculated on the basis of the size variable amount 991and the angle variable amount 992 created by rendering the image of thetemplate candidate 710 variable in pattern matching (S211). When theinspected pattern 830 is different from the template candidate 710 to besearched, the search inside the designated range 820 is continued. Whilethe steps described above are repeated (S207 to S209), the inspectedpattern 830 satisfying the correlation coefficient 910 is registered andthe processing is continued until the search inside the designated range820 is completed.

Pattern matching described above is executed by using geometric patternmatching, for example. The feature points of the image data areextracted by feature point extraction unit such as Moravec operator,SUSAN (Smallest Univalue Segment Assimilating Nucleus), MIC (MinimumIntensity Charge), or the like. The feature point extraction unit can beset by feature point extraction setting unit 921 such as the inputspace, icons or buttons provided on the template evaluation settingscreen. Incidentally, it is also possible to execute pattern matching onthe basis of the feature points by extracting the positional coordinatesof the corners (corners of wiring pattern) of the inspected pattern 830and the number of corners as the feature points from the segmented imagedata. The degree of coincidence of the feature points is differentdepending on the mode of the template candidate 710 to be searched andon the manufacturing process of the semiconductor wafer 1. It istherefore preferred to appropriately select an optimal method dependingon the condition of use.

FIG. 10 shows a display screen showing the inspection result of theinspected pattern 830 detected from the template evaluation designatedcoordinates 810. The inspected pattern 830 satisfying the correlationcoefficient 910 by pattern matching is displayed on the display device1020 in a list form (analytical result display means) in associationwith various evaluation data such as a precedence 1010 of the scorevalue, the image of the template candidate 710, the score value 1020,the acquired image 1030, the coordinates 1070, the judgment result 1040,the angle correction value 1050, the size correction value 1060, and soforth (S212). This display can be changed in the ascending or descendingorder of the score values 1020 by setting. When the template processselection unit 960 is automatic setting 970, the highest score value1020 is automatically employed as the screen of the template. As thetemplate candidate 710 that proves optimal is selected in this way onthe basis of the analyzing means of the foreign matter inspectionapparatus, the mismatching between human judgment and machine judgmentcan be suppressed and the optimal template can be selected. Thisselection of the template candidates 710 can also be set manually(manual setting 980), and the image that is believed appropriate can beselected as the template from the list display while looking up theacquired image 1030 and the score value 1020.

Next, the inspection stage chuck 42 is moved to the coordinates of theinspected pattern selected as the template (S213) and the angle of theinspection stage chuck 42 is changed for each angle resolution 940(S214). The image position of the inspected pattern 830 is corrected(S215) and while the image data of the inspected pattern 830 is taken bythe CCD camera for each angle (S216), the image data of the inspectedpattern is registered as the template to the storage device 160 (S217).The processing is continued until imaging within the range set to theangle correction range 941 is completed (S214 to S218). After imaging ofthe image data group of the template for which angle correction degreeis shifted is completed, the semiconductor wafer 1 is transferred fromthe inspection stage chuck 42 and is recovered into the wafer cassette11 (S219). A plurality of template images the angles of which are madedifferent from one another in advance is prepared and pattern matchingis then executed by using the image data group the angles of which areshifted to improve identification accuracy of the patterns. The angleshift amount can be detected or anticipated from the image data of theimage data group after pattern matching and θ correction can be made bypattern matching by using one alignment mark (first alignment mark 312or second alignment mark 322) on the basis of the shift amount. Rough θcorrection becomes possible when the angle difference of thesemiconductor wafer 1 is great, and the correction speed as well asthrough-put of the correction processing can be improved.

In this embodiment, after the template candidate is selected as thetemplate, the image data group generated by shifting the angle as thebasic image data for angle correction is taken. However, it is alsopossible to execute this imaging process when the inspected pattern 830is detected at the time of search inside the designated range 820 inpattern matching. In this way, the template search can be automated andthe operation factor can be improved. To suppress the increase of thescale of the system as the image data collected increases, however, theimage data group is preferably collected after the template is selected.

When the angle difference of the semiconductor wafer 1 is slight and theimage data group and rough θ correction are not required or when thesearch processing speed of the template candidate 710 is of importance,the corresponding process steps can be skipped. Also, the dataprocessing method can be changed through setting from the input device110.

The edge position 440 is detected in the image data collected by thesame method as that of the first embodiment and is likewise registeredto the storage device 160. The image data and the edge position 440 areused as the template. After the template is evaluated, the semiconductorwafer 1 is recovered into the wafer cassette in the same way as in thefirst embodiment.

Embodiment 3

Next, a method for detecting the alignment marks formed on thesemiconductor wafer 1 will be explained with primary reference to FIGS.11, 12 and 16. However, the explanation of those portions which overlapwith the first and second embodiments will be omitted and reference willbe made also to FIGS. 1 and 2, whenever necessary.

FIG. 16 is a flowchart showing a processing procedure of thesemiconductor wafer 1 in the third embodiment and FIG. 11 shows a setscreen for detecting the alignment marks formed on the semiconductorwafer 1. The semiconductor wafer 1 as the measurement object istransferred by the wafer cassette 11 with the execution of the transferprogram (S301) in the same way as in the first embodiment and is put onthe inspection stage chuck 42 (S302 to S304). The inspection stage chuck42 is then moved to the position of the designated chip 1210 inaccordance with setting of the set screen (S305). After positioning ismade to the designated coordinates 1220 of the designated chip 1210, theinspection range 1230 is scanned by the CCD camera (S306), the meandensity waveform is collected by the same method as that of the firstembodiment while imaging is made, and the edge position 440 is detected(S307 to S308). When an inspection object satisfying the edge positionnumber 1250 is detected in the image rang 1240 set (S309), theinspection object is registered with the feature points such as theimage data of the inspection object and its coordinates, the calculatededge number, and so forth, to the storage device 160 (S310). While theinside of the designated range 1220 is searched, the inspected object isregistered (S306 to S310) and imaging is completed with completion ofthe designated range.

The registered image data is displayed in the list form either in anascending order or a descending order of the numerical values of theedge position number 1250 on the display screen of the collected imageof the inspection object in the display device 120 shown in FIG. 12(S311). The image data of the inspection object displayed on the displaydevice 120 is selected and the inspection stage chuck 42 is moved to thedesignated coordinates by selecting the buttons of movement indicationunit 1310 through the input device 110 to confirm the inspection objectwith eye. Alternatively, the buttons of registration indication unit1320 are selected to directly register the inspection object as thetemplate (S312). When reliability is low, the image of the inspectionobject is collected in the same way as in the second embodiment and canbe registered as the template. Incidentally, the buttons described abovemay well be input unit capable of inputting the signals and are notparticularly limited. Therefore, input unit such as icons and keyboardscan be employed.

Embodiment 4

Next, a template reliability evaluation method for evaluatingreliability as to whether or not the selected template candidate 710 iseffective as the template and whether or not other pattern formed on thesemiconductor wafer 1 is mistaken as the template candidate will beexplained with primary reference to FIGS. 13 and 17. The explanation ofthose portions which overlap with those of the embodiments 1, 2 and 3will be omitted and reference will be made also to FIGS. 1 and 2,whenever necessary.

FIG. 13 shows an operation screen used for evaluating templatereliability and FIG. 17 shows a flowchart of the processing procedure.The operation screen for template reliability evaluation shown in FIG.13 includes registration number input unit 1410 for inputting theregistration number of the template, display indication unit 1413 fordisplaying the image of the registration number, registration imagedisplay unit 1411 for executing collective thumbnail display of thetemplate images, selection unit 1412 for deciding the template candidate710 for which reliability evaluation is to be made, correlationcoefficient setting unit 1460 for pattern matching, score thresholdvalue setting unit 1450 for setting the threshold value of the scorevalue, chip setting unit 1430 for designating the chip inside thesemiconductor wafer to be inspected, coordinates setting unit 1431 fordesignating the coordinates inside the chip as the starting point, andinside-chip inspection range setting unit 1440 for setting theinspection range. The operation screen is constituted as a set screen onthe display device 120 in such a fashion that the set value can bechanged. The operation screen further has displaying functions by usingimage display unit 1420 for displaying the registration data of thetemplate candidate 710 as the image at the time of registration,inside-chip coordinates display unit 1421 for displaying a relativeposition inside the chip, feature point number display unit 1422 fordisplaying the number of the feature points such as the edge, scorevalue displaying unit 1423 for displaying the matching state of thefeature points, correlation coefficient display unit 1425 for displayingthe pattern matching state, and manufacturing process display unit 1424for displaying a manufacturing process of the semiconductor wafer 1. Asthe reference data is displayed at the time of collection of thetemplate candidate 710, the artificial setting mistake can be decreasedand setting of the conditions for reliability evaluation becomes easy.Incidentally, though these input unit and display unit are constitutedby buttons in this embodiment, other unit can be used as long as theycan input and transmit the signals and can make display. Icons,keyboards and other signal input/transmitting unit and displaying unitmay be used.

When the buttons disposed on the screen of the display device 120 areselected, the screen is displayed (S401). The group of the templatecandidates 710 stored in the storage device 160 is displayed inthumbnail display on the display screen (not shown) set separately. Anarbitrary template candidate 710 is selected from the group of thetemplate candidates 710 by candidate selection means (not shown) and thedata of this template candidate 710 is read out from the storage device160. When the registration number of the template candidate 710 isalready known, it is possible to directly input the registration numberby the input device 110 to the registration number input unit 1410, forexample, to read the data by the display indication unit 1413 and toconfirm the template candidate 710 by the image displaying unit 1420.Next, selection is made by the selection unit 1412 and the templatecandidate 710 is selected as the one for which reliability evaluation isto be made (S402). Incidentally, though reliability evaluation is madeon the basis of one template candidate 710 in this embodiment, it isalso possible to set two or more template candidates 710 and tosimultaneously execute reliability evaluation. The evaluation timenecessary for selecting the template can thus be shortened.

The semiconductor wafer 1 as the measurement object is transferred fromthe wafer cassette 11 by the same method as that of the first embodimenttogether with the execution indication unit 1470 of a reliabilityevaluation program and is put on the inspection stage chuck 42 (S403 toS405). The inspection stage chuck 42 is thereafter moved to the setposition of the first chip setting unit 1430 in accordance with settingof the set screen (S406). Next, after the position is adjusted to theset position of the coordinates setting unit 1431 of the chip, the imagedata of the inspected object (pattern) formed on the semiconductor wafer7 is collected (S408) while the set range of the inside-chip inspectionrange setting unit 1440 is scanned by the CCD camera (S407). Whether ornot the predetermined value of the correlation coefficient thresholdvalue setting unit 1460 is satisfied is judged while pattern matching isbeing executed (S409). The feature points are extracted by the edgedetection shown in the first embodiment, etc from the inspected object(pattern) satisfying the predetermined correlation coefficient and thescore value is calculated on the basis of the feature points (S410). Thecoordinates of the inspected object (pattern) satisfying the score valueof the core threshold value setting unit 1450 are collected and areregistered to the storage device 160 with the image data and the featurepoints such as the correlation coefficient and the score value (S411).Because the degree of pattern matching can be adjusted by thecorrelation coefficient threshold value setting unit 1460, theinfluences of contrast that changes in the manufacturing process can besuppressed. The number of the inspected objects (patterns) sampled canbe controlled by the score threshold value setting unit 1450 and theextension of the inspection time can be suppressed. The inspected object(patterns) satisfying the condition are registered on occasion while theinside-chip inspection range 1440 is searched (S407 to S411) and theprocess is moved to the set position of the next chip setting unit 1430with completion of scanning of the inside-chip inspection range 1440(S406). Search of similar inspected object (patterns) is repeated andimaging is completed when the inspection of all the chips set by thechip setting unit 1430 is completed.

After all the chips set by the chip setting unit 1430 are inspected, thedata of the object matters saved in the storage device 160 are displayedin the list form (not shown in the drawings) on the set screen disposedon the screen of the display device 120 (S412). This list is generatedby associating the template candidate 710 with the image data of theinspected object (pattern) sampled and the feature points and aredisplayed in the ascending or descending order for each chip set by thechip setting unit 1430 on the basis of the numerical values representingthe degree of similarity such as the score value and the correlationcoefficient. Whether the candidate is suitable as the template can bejudged from the score value and the numerical value of the correlationcoefficient and the possibility of the recognition mistake can be judgedfrom the sizes of the score values and the correlation coefficientsbetween the inspected object (patterns) and the sizes of the correlationcoefficients. Stability of pattern matching can be judged from the orderof the inspected object (patterns) and the difference of the numericalvalues among the chips set by the chip setting unit 1430. The templatecandidate 710 is selected by referring to the result of the list and thetemplate selection unit (not shown) arranged on the screen of thedisplay device 120 is selected. The candidate is thus registered as thetemplate (S413).

Incidentally, when a plurality of template candidates is evaluated, thedata processing unit 50 judges and adopts a suitable template candidate710 from the relation described above by selecting the automaticselection unit. However, it is also possible to confirm the condition ofthe list display by employing manual setting and to select the templatecandidate 710. When this manual setting is employed, reliability can bere-evaluated by selecting the re-execution indication unit 1471 bychanging various kinds of setting when the evaluation result of the listdisplay is not satisfactory, for example. When various kinds of settingare not changed, in particular, re-evaluation can be of course made.Because this evaluation can compare and evaluate a plurality of templatecandidates 710 under the same condition such as the θ angle error of thesemiconductor wafer 1, for example, the evaluation method is effectivefor shortening the evaluation time and selecting a template having highreliability. However, the template registration step (S413) is notindispensable and may be skipped when only reliability evaluation of thetemplate candidates is made. The wafer is transferred with completion ofthe evaluation by the same method as that of the first embodiment and isrecovered into the original wafer cassette 11, and the program iscompleted (S414 to S415). Reliability and operation factor of theforeign matter inspection apparatus can be drastically improved becauseselection of the template candidates 710 and the set value of thethreshold value for avoiding the possibility of the recognition mistakeof the inspected object and the recognition mistake itself can beconfirmed in advance owing to this reliability evaluation function.

When the reliability evaluation program gets frozen due to therecognition mistake during evaluation, the evaluation can be interruptedor stopped by using the interruption indication unit 1480 or the stopindication unit 1490. Furthermore, the inspection apparatus can berestored to the initial state by releasing the error by selecting therestoration unit 1491.

Embodiment 5

An inspection apparatus for an inspected object according to stillanother embodiment of the invention will be explained. FIG. 18 shows aconstruction of the inspection apparatus in this embodiment. In thedrawing, reference numeral 1810 denotes a stage for moving and rotatinga wafer 1819. Reference numeral 1811 denotes an optical device forirradiating the surface of the wafer 1819. Reference numeral 1812denotes a camera for imaging the surface of the wafer 1819 irradiated bythe optical device 1811. Reference numeral 1813 denotes a capture boardfor storing the surface image of the wafer 1819 taken by the camera1812. Reference numeral 1814 denotes image data stored by the captureboard 1813. Reference numeral 1815 denotes a main storage for subjectingthe image data 1814 to processing. Reference numeral 1816 denotes animage processor for processing the image data 1814. Reference numeral1817 denotes a storage controller having stage controlling software forcontrolling the stage 1810. Reference numeral 1818 denotes a stagecontroller for controlling the stage 1810. Reference numeral 1819constitutes software.

FIG. 19 shows an arrangement of correction marks formed on the wafer1819 according to this embodiment. Reference numerals 1901 and 1902denote correction marks, respectively, and reference numeral 1903denotes a confirmation mark. The confirmation mark may exist at anyposition as long as it exists in the proximity of the correction mark1902.

FIG. 20 shows an orbit of the wafer 1819 from its transfer to the stage1810 to its positioning. Reference numeral 2009 denotes the position ofthe wafer 1819 immediately after it is transferred to the stage 1810.Reference numeral 2000 denotes the center of revolution of the stage1810. Reference numeral 2001 denotes the center of the wafer when thewafer 1819 exists at the position 2009. Reference numerals 2003, 2004and 2005 denote coordinate positions of the correction marks 1, 2 and 3,respectively, when the wafer centers 2003, 2004 and 2005 exist at theposition 2009. Reference numeral 2010 denotes the position of the wafer1819 after positioning is made. Reference numerals 2006, 2007, 2008 and2009 denote the coordinate positions of the correction marks 1, 2 and 3,respectively, when the wafer 1819 exists at a position 2100.

FIG. 21 shows the flow of an alignment process in this inspectionapparatus.

In step S500, the stage 1810 is moved to a coordinate position P1(x1,y1) of the correction mark 1901 registered in advance. The correctionmark 1901 is imaged by the camera 1812 in step S501. Pattern matching isexecuted for the image taken in step S502 and the coordinate position ofthe correction mark 2003 is detected. At this time, the wafer 1819exists at the position 2009 while it is transferred by the stage 1810and the correction mark 1 exists at the coordinate position 2003. Afterthe coordinate position of 2003 detected is acquired in step S502, thestage 1810 is moved to the coordinate position of the correction mark 2registered in advance in step S503. At this time, the wafer 1819 existsat the position 2009 while transferred by the stage 1810 and thecorrection mark 2 exists at the coordinate position 2004. The image ofthe correction mark 2 is taken by the camera 1812 in step S504. Patternmatching is executed for the image taken in step S505 and the coordinateposition of the correction mark 2 is detected. A correction angle iscalculated in step S506 from the coordinate positions 2003 and 2004 ofthe correction marks 1 and 2 detected in step S502 and S505. The thirdcoordinates before position correction is made are determined in stepS507 from the correction angle calculated in S506, from the coordinatesof the first correction mark calculated in step S502 and from thecoordinates of the third confirmation mark registered in advance. Instep S508, the coordinate position when the stage 1810 is rotated to thecorrection angle is calculated with respect to the coordinates of thethird confirmation mark calculated in step S507. In step S509, the stage1810 is rotated by the correction angle calculated in step S506 and ismoved to the coordinate position calculated in step S509. Imaging of theconfirmation mark 3 is executed by the camera 1812 in step S510. Thecoordinates 2008 of the confirmation mark 3 are detected by patternmatching in step S511. In step S512, the difference is calculatedbetween the coordinate position 2008 of the correction mark 3 calculatedin step S508 and the coordinate position 2008 of the correction mark 3measured in step S511. Position correction is completed when thedifference value is within a threshold value that is registered inadvance. When the difference value is greater than the threshold value,the process steps from S503 are repeated. The embodiments of theinvention are not particularly limited to those described above but canbe changed or modified in various ways within the scope of theinvention.

Although the invention has thus been explained about the foreign matterinspection apparatus for the manufacture of semiconductor integratedcircuits by way of example, the alignment technology according to theinvention can be widely applied to various process steps and apparatusesnecessary for producing disks, flat panel display devices, masks, and soforth, produced from flat panels such as substrates of flat paneldisplay devices glass substrates of TFT and ALTIC substrates.

Although the invention has been explained about the embodiments of theforeign matter inspection apparatus, the invention can be similarlyapplied to semiconductor inspection apparatuses and semiconductormanufacturing apparatuses without particular limitation. For example,the invention can be applied to measuring apparatuses and exposureapparatuses such as CD-SEM as long as they can execute positioncorrection processing of inspected objects by using alignment marksformed on the inspected objects.

It should be further understood by those skilled in the art thatalthough the foregoing description has been made on embodiments of theinvention, the invention is not limited thereto and various changes andmodifications may be made without departing from the spirit of theinvention and the scope of the appended claims.

1. A foreign matter inspection apparatus for inspecting existence offoreign matters on a surface of an inspected object from a receptionintensity of reflected or scattered beams from said inspected object byirradiating optical beams to the surface of said inspected object,comprising: a device for collecting a first image datum of an alignmentmark formed on the surface of said inspected object; a device forregistering a second image datum of a template; a first data processorfor normalizing said first image datum, calculating a first edgeintensity waveform representing a change of contrasting-density of saidnormalized first image datum, and executing a first correction of saidfirst edge intensity waveform on the basis of a first coefficient; asecond data processor for normalizing said second image datum,calculating a second edge intensity waveform representing a change ofcontrasting-density of said normalized second image datum, and executinga second correction of said second edge intensity waveform on the basisof a second coefficient; and a third data processor for executing apattern-matching between an image of the inspected object and thetemplate on the basis of the corrected first edge intensity waveform forthe normalized first image datum and the corrected second edge intensitywaveform for the normalized second image datum.
 2. The foreign matterinspection apparatus according to claim 1, further comprising: a fourthdata processor for calculating an index value on the basis of a thirdfeature point, wherein said third feature point is a feature point of analignment mark which is related with a datum executed said secondcorrection.
 3. The foreign matter inspection apparatus according toclaim 2, further comprising: a display device for displaying pluralinspection patterns in the order of plural index values.
 4. A foreignmatter inspection apparatus for inspecting the existence of foreignmatters on a surface of an inspected object by irradiating optical beamsto the surface of said inspected object, acquiring an image signal froma reception intensity of reflected or scattered beams and comparing saidimage signal with an image signal acquired from an adjacent inspectedobject, comprising: image processing means for extracting feature pointsof alignment marks formed on the surface of said inspected object andconducting pattern matching with feature points of a template;processing unit for calculating a probability or score from both of saidfeature points subjected to pattern matching; judgment processing unitfor identifying an alignment mark as a reference when said featurepoints are coincident with one another with a predetermined probabilityor score; another processing unit for calculating a difference amount ofsaid inspected object from coordinates collected by recognition of atleast two alignment marks inside said inspected object; and driving unitfor conducting alignment by moving an inspection stage on the basis ofsaid difference amount.
 5. A foreign matter inspection apparatus forinspecting existence of foreign matters on a surface of an inspectedobject from a reception intensity of reflected or scattered beams fromsaid inspected object by irradiating optical beams to the surface ofsaid inspected object, comprising: a device for collecting a first imagefeature point of an alignment mark formed on the surface of saidinspected object; a device for registering a second image feature pointof a template; a first data processor for normalizing said first imagefeature point, calculating a first edge intensity waveform representinga change of contrasting-density of said normalized first image featurepoint, and executing a first correction of said first edge intensitywaveform on the basis of a first coefficient; a second data processorfor normalizing said second image feature point, calculating a secondedge intensity waveform representing a change of contrasting-density ofsaid normalized second image feature point, and executing a secondcorrection of said second edge intensity waveform on the basis of asecond coefficient; and a third data processor for executing apattern-matching between an image of the inspected object and thetemplate on the basis of the corrected first edge intensity waveform forthe normalized first image feature point and the corrected second edgeintensity waveform for the normalized second image feature point.